Migrating from IPv4 to IPv6: Complete Overview Guide
- Describe the primary differences between IPv4 and IPv6
- Understand operations of IPv6, RIPng, OSPFv3, DHCPv6, NAT-PT, MBGP, BGP4+, and transition technologies
- Design an IPv6 infrastructure solution for enterprise needs
- Design OSPFv3 routing solutions to meet organizational requirements
Table of Contents
- Why IPv6?
- What's New in IPv6?
- Simplification of Header Format
- Unicast, Multicast, and Anycast Addresses
- Address Notation
- Prefix Notation
- Global Routing Prefixes
- Interface IDs and EUI-64
- Special Addresses
- IPv6 Addresses with Embedded IPv4 Addresses
- 6to4 Addresses
- Link-Local and Unique Local Addresses
- Anycast Addresses
- Multicast Addresses
Why IPv6?
The IP version currently used in networks and the Internet is IP version 4 (IPv4). IPv4 was developed in the early '70s to facilitate communication and information sharing between government researchers and academics in the United States. At the time, the system was closed with a limited number of access points, and consequently the developers didn't envision requirements such as security or quality of service.
To its credit, IPv4 has survived for over 50 years and has been an integral part of the Internet revolution. But even the most cleverly designed systems age and eventually become obsolete. This is certainly the case for IPv4. Today's networking requirements extend far beyond support for web pages and email. Explosive growth in network device diversity and mobile communications, along with global adoption of networking technologies, new services, and social networks, are overwhelming IPv4 and have driven the development of a next-generation Internet Protocol.
The Evolution and Maturity of IPv6
IPv6 has been developed based on the rich experience we have from developing and using IPv4. Proven and established mechanisms have been retained, known limitations have been discarded, and scalability and flexibility have been extended. IPv6 is a protocol designed to handle the growth rate of the Internet and to cope with the demanding requirements on services, mobility, and end-to-end security.
When the Internet was switched from using Network Control Protocol (NCP) to Internet Protocol (IP) in one day in 1983, IP was not the mature protocol that we know today. Many of the well-known and commonly used extensions were developed in subsequent years to meet the growing requirements of the Internet. In comparison, hardware vendors and operating system providers have been supporting IPv6 since 1995 when it became a Draft Standard. In the decade since then, those implementations have matured, and IPv6 support has spread beyond the basic network infrastructure and will continue to be extended.
Address Space Crisis and Regional Distribution
For historic reasons, organizations and government agencies in the United States used the largest part of the allocatable IPv4 address space. The rest of the world had to share what was left over. Some organizations used to have more IPv4 address space than the whole of Asia (where more than 50% of the world's population live). This is one explanation of why the deployment of IPv6 in Asia is much more common than in Europe and the United States.
The IPv4 address space has a theoretical limit of 4.3 billion addresses. However, early distribution methods allocated addresses inefficiently. Consequently, some organizations obtained address blocks much larger than they needed, and addresses that could be used elsewhere are now unavailable. If it were possible to reallocate the IPv4 address space, it could be used much more effectively, but this process is not possible, and a global reallocation and renumbering is simply not practical. In addition to that it would not buy much, as even 4.3 billion addresses would not suffice for long at the current growth rate.
We have to take into account that in the future we will need IP addresses for billions of devices. Vendors in all industries are developing monitoring, control, and management systems based on IP. The Autoconfiguration capability of IPv6 will be a necessity for many complex networks of today and tomorrow, and for the number of IP devices of all types. The management of such services can't be accomplished with traditional addressing methods, and Stateless Address Autoconfiguration will also help to reduce administrative costs for organizations.
The Problem with NAT
The extended address space and the restoration of the original end-to-end model of the Internet allows for the elimination of Network Address Translation (NAT), in which a single or a few public IPv4 address(es) are used to connect a high number of users with private addresses to the Internet by mapping the internal addresses to the public address(es). NATs were introduced as a short-term fix for solving the address space limitations with IPv4, since IPv6 was not ready yet (refer to RFC 1631; the original NAT specification was obsoleted by RFC 3022 in 2001).
NATs have become pretty common in IPv4 networks, but they create serious disadvantages in management and operation: in order to do the address mapping, NATs modify end node addresses in the IP header. Very often, Application Level Gateways (ALG) are used in conjunction with NAT to provide application-level transparency. There is a long list of protocols and applications that create problems when used in a NAT environment. IPsec and peer-to-peer applications are two well-known examples.
Broadband Growth and Connected Devices
By introducing a more flexible header structure (Extension headers), the protocol has been designed to be open and extensible. In the future, new extensions can easily be defined and integrated in the protocol set. Based on the fact that IPv4 has been in use for more than 50 years, the development of IPv6 was based on the experience with IPv4 and focused on creating an extensible foundation; you can expect it to last a long time.
Broadband penetration rates in many countries continue to accelerate and, in some cases, have reached 65% or more. This level of always-on connectivity with substantial bandwidth capacity means that there is greater opportunity for devices to be connected. And many consumer electronic manufacturers have taken advantage of this. Online gaming is no longer the sole purview of games on PCs.
Gaming stations, such as Sony's PlayStation, Xbox, or Nintendo, have added capabilities to take them online. Many telecommunication carriers are providing television-type services (movies, audio content, etc.) over their IP networks. Even appliances, such as refrigerators, stoves, water heaters, and bathtubs, are getting connected. Many of these devices are being connected to facilitate things such as power management, remote control, and troubleshooting, and for telemetry/monitoring purposes.
The Wireless and Mobility Revolution
The growth of the wireless industry (both cellular and wireless networks) has been nothing short of phenomenal. In more and more countries the number of cell phones actually exceeds the number of people. In this world of continuous reachability and reliance on the ability to access information at any time, the mobility requirements for end users have become exceptionally important. From the carriers' perspective, especially those supporting multiple media access, leveraging IP as the method of transporting and routing packets makes sense. Smartphones access the Internet, play games with other users, make phone calls, and even stream video content.
Instead of supporting all of these functions using different transport protocols and creating intermediary applications to facilitate communications, it is far more efficient to leverage the existing network infrastructure of the Internet and a company's network. From a technical perspective, Mobile IPv6 is very elegant in its design, supporting mobile users in a highly efficient manner and providing the overlay mechanisms for users to maintain their connections when moving between networks, even if those networks do not use the same type of media access.
What's New in IPv6?
IPv6 is an evolution of IPv4. The protocol is installed as a software upgrade in most devices and operating systems. If you buy up-to-date hardware and operating systems, IPv6 is usually supported and needs only activation or configuration. In many cases it is activated by default. Currently available transition mechanisms allow the step-by-step introduction of IPv6 without putting the current IPv4 infrastructure at risk. Here is an overview of the main changes:
Extended Address Space
The address format is extended from 32 bits to 128 bits. This provides multiple IP addresses for every grain of sand on the planet. In addition, it also allows for hierarchical structuring of the address space in favor of optimized global routing.
Autoconfiguration
Perhaps the most intriguing new feature of IPv6 is its Stateless Address Autoconfiguration (SLAAC) mechanism. When a booting device in the IPv6 world comes up and asks for its network prefix, it can get one or more network prefixes from an IPv6 router on its link. Using this prefix information, it can autoconfigure for one or more valid global IP addresses by using either its MAC identifier or a private random number to build a unique IP address.
In the IPv4 world, we have to assign a unique IP address to every device, either by manual configuration or by using DHCP. SLAAC should make the lives of network managers easier and save substantial cost in maintaining IP networks.
Simplification of Header Format
The IPv6 header is much simpler than the IPv4 header and has a fixed length of 40 bytes. This allows for faster processing. It basically accommodates two times 16 bytes for the Source and Destination address and only 8 bytes for general header information.
Improved Support for Options and Extensions
IPv4 integrates options in the base header, whereas IPv6 carries options in so-called Extension headers, which are inserted only if they are needed. Again, this allows for faster processing of packets. The base specification describes a set of six Extension headers, including headers for routing, Quality of Service, and security.
The IPv4 Address Space and IPv6 Address Types
An IPv4 address has 32 bits and looks familiar. An IPv6 address has 128 bits and looks wild at first glance. Extending the address space was one of the driving reasons to develop IPv6, along with optimization of routing tables, especially on the Internet. This section will help you become familiar with the extended address space and will also explain how IPv6 addressing works and why it has been designed to be the way it is. There is a lot more to understand than just the 128-bit address. The address architecture has been extended and the large address space offers opportunity for new address designs. The IPv6 addressing architecture is defined in RFC 4291.
IPv4 knows unicast, broadcast, and multicast addresses. With IPv6, the broadcast address is not used anymore; multicast addresses are used instead. This is good news because broadcasts are a problem in most networks. The anycast address, a type of address introduced with RFC 1546, has already been used in the IPv4 world but will be used on a wider basis with IPv6.
Unicast, Multicast, and Anycast Addresses
An IPv6 address can be classified into one of three categories:
| Address Type | Description |
|---|---|
| Unicast | A unicast address uniquely identifies an interface of an IPv6 node. A packet sent to a unicast address is delivered to the interface identified by that address. |
| Multicast | A multicast address identifies a group of IPv6 interfaces. A packet sent to a multicast address is processed by all members of the multicast group. |
| Anycast | An anycast address is assigned to multiple interfaces (usually on multiple nodes). A packet sent to an anycast address is delivered to only one of these interfaces, usually the nearest one. |
Some General Rules
IPv6 addresses are assigned to interfaces as in IPv4, not to nodes as in OSI, so each interface of a node needs at least one unicast address. A single interface can also be assigned multiple IPv6 addresses of any type (unicast, multicast, and anycast). A node can therefore be identified by the address of any of its interfaces. It is also possible to assign one unicast address to multiple interfaces for load-sharing reasons, but if you do this, you need to make sure that the hardware and drivers support it.
Address Notation
An IPv6 address has 128 bits, or 16 bytes. The address is divided into eight 16-bit hexadecimal blocks separated by colons. For example:
2001:0db8:0000:0000:0262:b3ff:fe1e:8329
To make life easier, some abbreviations are possible. For instance, leading zeros in a 16-bit block can be skipped. The example address now looks like this:
2001:db8:0:0:262:b3ff:fe1e:8329
A double colon can replace consecutive zeros or leading or trailing zeros within the address. If we apply this rule, our address looks as follows:
2001:db8::262:b3ff:fe1e:8329
So the IPv6 address 2001:0db8:0000:0000:0056:abcd:0000:1234 can be represented in the following ways (note the two possible positions for the double colon):
2001:0db8:0000:0000:0056:abcd:0000:1234 2001:0db8:0:0:56:abcd:0:1234 2001:0db8::56:abcd:0:1234 2001:0db8:0:0:56:abcd::1234
Standardization of Address Representation
There are so many different ways to write and abbreviate IPv6 addresses and this can cause operational troubles. If you want to do lookups in a database or a spreadsheet, you have to make sure that everybody uses the same format to store addresses; otherwise, you won't be able to find out if an address is already in the list. For this purpose the best option is probably to just use the full format, as it's the only unambiguous format. Also be aware that some systems are case sensitive, so you need to define whether to use capitals or not.
For the purpose of making administration easier, an RFC was written to standardize IPv6 address representation. It also discusses the issues that can arise when storing IPv6 addresses in databases and spreadsheets for lookup. You need solid rules for address representation to be able to find addresses. Probably for these cases it is best to use the full address representation, as it is the only unambiguous one. For all other cases, RFC 5952 recommends using the following rules:
- Leading zeros must be suppressed.
- A single 16-bit 0000 field must be represented as 0 and should not be replaced by a double colon.
- Shorten as much as possible.
- Use a double colon whenever possible.
- Always shorten the largest number of zeros.
- If two blocks of zero are equally long, shorten the first one.
- Use lowercase for a, b, c, d, e, f.
Mixed IPv4/IPv6 Notation
In environments where IPv4 and IPv6 nodes are mixed, another convenient form of IPv6 address notation is to put the values of an IPv4 address into the four low-order bytes of the address. An IPv4 address of 192.168.0.2 can be represented as x:x:x:x:x:x:192.168.0.2, and an address of 0:0:0:0:0:0:192.168.0.2 can be written as ::192.168.0.2. If you prefer, you can also write ::C0a8:2. This is the hex representation for 192.168.0.2.
For the representation of an IPv6 address followed by a port number, the best way is to put the IPv6 address in square brackets, followed by a colon and the port number. So it may look like this:
[2001:db8::1]:443
Prefix Notation
The notation for prefixes has also been specified in RFC 4291. A global routing prefix is the high-order bits of an IP address used to identify the subnet or a specific type of address. It was called the format prefix in earlier RFCs. The prefix notation is very similar to the way IPv4 addresses are written in CIDR (Classless Interdomain Routing) notation, and it is also commonly used for subnetted IPv4 addresses. The notation appends the prefix length, written as a number of bits with a slash, which leads to another format:
IPv6 address/prefix length
The prefix length specifies how many leftmost bits of the address specify the prefix. This is another way of noting a subnet mask. Remember, a subnet mask specifies the bits of the IPv4 address that belong to the network ID. The prefix is used to identify the subnet that an interface belongs to and is used by routers for forwarding.
Consider the IPv6 prefix notation 2001:db8:1200::/40. The /40 indicates that the first 40 bits represent the network prefix, and the remaining 88 bits are available for host addressing within that network.
Global Routing Prefixes
The current assignment of reserved prefixes and special addresses, such as link-local addresses or multicast addresses, is outlined in the IPv6 address architecture. The major part of the address space (over 80 percent) is unassigned with the exception of a few special cases. This leaves room for future assignments. All address ranges not listed in the standard tables are currently reserved or unassigned. The Internet Assigned Numbers Authority (IANA) currently assigns only out of the binary range starting with 001.
Some special addresses are assigned out of the reserved address space with the binary prefix 0000 0000. These include the unspecified address, the loopback address, and IPv6 addresses with embedded IPv4 addresses, which we discuss in detail later.
Unicast addresses can be distinguished from multicast addresses by their prefixes. Globally unique unicast addresses have a high-order byte starting with 001. An IPv6 address with a high-order byte of 1111 1111 (ff in hex) is always a multicast address. Anycast addresses are taken from the unicast address space, so they can't be identified as anycast just by looking at the prefix. If you assign the same unicast address to multiple interfaces, thereby making it an anycast address, you have to configure the interfaces so they all know that this address is an anycast address.
Global Unicast Address Format
Global unicast addresses are identified by the binary prefix 001. RFC 4291 defines the global unicast address format as follows:
| Field | Description |
|---|---|
| Global Routing Prefix | The global routing prefix identifies the address range allocated to a site. This part of the address is assigned by the international registry services and the Internet Service Providers (ISPs) and has a hierarchical structure. |
| Subnet ID | The subnet ID identifies a link within a site. A link can be assigned multiple subnet IDs. A local administrator of a site assigns this part of the address. |
| Interface ID | The interface ID identifies an interface on a subnet and must be unique within that subnet. The interface ID is always 64 bits, so therefore an IPv6 subnet is always a /64 subnet. |
International Registry Services and Current Address Allocations
The international allocation of IPv6 addresses has been delegated to several regional registry services:
- ARIN (American Registry for Internet Numbers) for North America and Sub-Saharan Africa
- RIPE NCC (Reseau IP Europeens Network Coordination Centre) for Europe, the Middle East, Central Asia, and North Africa
- APNIC (Asia Pacific Network Information Centre) for the Asia/Pacific region
- LACNIC (Latin American and Caribbean Internet Addresses Registry) for Latin America
- AfriNIC (African Network Information Centre) went into operation in 2005 to cover Africa in the future
Each of these registries has information on its site about address allocation issues, current practices, and procedures.
The Interface ID
Addresses in the prefix range 001 to 111 should use a 64-bit interface identifier that follows the EUI-64 (Extended Unique Identifier) format (except for multicast addresses with the prefix 1111 1111). The EUI-64 is a unique identifier defined by the Institute of Electrical and Electronics Engineers (IEEE). Appendix A of RFC 4291 explains how to create EUI-64 identifiers.
An interface uses an identifier following the EUI-64 format during Stateless Address Autoconfiguration. For example, when an interface autoconfigures for a link-local address on an Ethernet interface using its MAC address, the 64-bit interface identifier has to be created from the 48-bit (6-byte) Ethernet MAC address.
Creating an EUI-64 Interface Identifier
First, the hex digits 0xff-fe are inserted between the third and fourth bytes of the MAC address. Then the universal/local bit, the second low-order bit of 0x00 (the first byte) of the MAC address, is complemented. The second low-order bit of 0x00 is 0, which, then complemented, becomes 1; as a result, the first byte of the MAC address becomes 0x02.
Therefore, the IPv6 interface identifier corresponding to the Ethernet MAC address 00-02-b3-1e-83-29 is 02-02-b3-ff-fe-1e-83-29. This example discusses only the EUI-64 creation process. Many other steps occur during Stateless Address Autoconfiguration.
fe80::/64 and a 64-bit interface identifier expressed in IPv6 colon-hexadecimal notation. Therefore, the MAC-based link-local address of the previous example interface, with prefix fe80::/64 and interface identifier 02-02-b3-ff-fe-1e-83-29, is fe80::0202:b3ff:fe1e:8329. This is described in RFC 2464, "Transmission of IPv6 Packets over Ethernet Networks."
Special Addresses
There are a number of special addresses that we need to discuss. The first part of the IPv6 address space with the prefix of 0000 0000 is reserved. Out of this prefix, special addresses have been defined as follows:
The Unspecified Address
The unspecified address has a value of 0:0:0:0:0:0:0:0 and is therefore also called the all-zeros address. It is comparable to 0.0.0.0 in IPv4. It indicates the absence of a valid address, and it can, for example, be used as a Source address by a host during the boot process when it sends out a request for address configuration information.
If you apply the notation conventions discussed earlier in this chapter, the unspecified address can also be abbreviated as ::. It should never be statically or dynamically assigned to an interface, and it should not appear as a Destination IP address or within an IPv6 Routing header. It is sometimes used in configuration files for software to tell a program to use any IPv6 address configured on an interface.
The Loopback Address
The IPv4 loopback address, 127.0.0.1, is probably familiar to you. It is helpful in troubleshooting and testing the IP stack because it can be used to send a packet to the protocol stack without sending it out on the subnet. With IPv6, the loopback address works the same way and is represented as 0:0:0:0:0:0:0:1, abbreviated as ::1. It should never be statically or dynamically assigned to an interface.
IPv6 Addresses with Embedded IPv4 Addresses
Because the transition to IPv6 will be gradual, two special types of addresses have been defined for backward compatibility with IPv4. Both are described in RFC 4291:
IPv4-Compatible Address (Deprecated)
This type of address is used to tunnel IPv6 packets dynamically over an IPv4 routing infrastructure. IPv6 nodes that use this technique are assigned a special IPv6 unicast address that carries an IPv4 address in the low-order 32 bits. This address type has so far rarely been used and was deprecated in RFC 4291. New or updated implementations will no longer need to support this type of address.
IPv4-Mapped IPv6 Address
This type of address is used to represent the addresses of IPv4-only nodes as IPv6 addresses. An IPv6 node can use this address to send a packet to an IPv4-only node. The address also carries the IPv4 address in the low-order 32 bits of the address.
The two addresses are pretty much the same. The only difference is the 16 bits in the middle. When they are set to 0, the address is an IPv4-compatible IPv6 address; if these bits are set to 1, it is an IPv4-mapped IPv6 address.
6to4 Addresses
The IANA has permanently assigned a 13-bit TLA* identifier for 6to4 operations within the global unicast address range (001). 6to4 is one of the mechanisms defined to let IPv6 hosts or networks communicate over an IPv4-only infrastructure. The prefix has a total length of 48 bits. The IPv4 address in the prefix must be a public IPv4 address and is represented in hexadecimal notation.
For instance, if you configure an interface for 6to4 with an IPv4 address of 62.2.84.115, the 6to4 prefix is 2002:3e02:5473::/48. Through this interface, all IPv6 hosts on this link can tunnel their packets over the IPv4 infrastructure.
Link-Local and Unique Local IPv6 Addresses
With IPv4, organizations often use IP addresses from the private ranges as defined in RFC 1918. The addresses reserved for private use should never be forwarded over Internet routers but should instead be confined to the organization's network. For connection to the Internet, Network Address Translation (NAT) maps internal private addresses to publicly registered IPv4 addresses. The original IPv6 specification allocated two separate address spaces (scopes) for link- and site-local use, both identified by their prefixes. The prefix for site-local addresses was fec0::/10.
Link-Local Addresses
A link-local address is for use on a single link and should never be routed. It doesn't need a global prefix and can be used for Autoconfiguration mechanisms, for Neighbor Discovery, and on networks with no routers, so it is useful for creating temporary networks.
In hexadecimal notation, a link-local address is identified by the prefix fe80::/10.
Unique Local IPv6 Unicast Addresses (ULA)
The replacement for site-local addresses is called Unique Local IPv6 Unicast Address (ULA). It is specified in RFC 4193. These addresses are globally unique but should not be routed to the global Internet. They are designed to be used within corporate sites or confined sets of networks.
The characteristics of unique local IPv6 unicast addresses are the following:
- Have a unique, global prefix which allows for filtering at network boundaries
- Allow for private connection of networks without the risk of address conflicts and the consequence of having to renumber one of the sites
- Are independent of ISP
- Can be used for internal communication without an Internet connection
- Can be used by applications just like regular global unicast addresses
For the unique-local IPv6 address, RFC 4193 specifies a prefix of fc00::/7. The 8th bit is currently set to 1 and specifies local administration of the prefix. Setting the 8th bit to 0 may be used in the future for centrally administrated addresses. For the moment, it was decided to standardize only a locally assigned version. The centrally assigned form may be defined in the future if a strong need is identified.
Anycast Address
Anycast addresses are designed to provide redundancy and load balancing in situations where multiple hosts or routers provide the same service. Anycast was not created for IPv6; it was defined in RFC 1546 in 1993 as an experimental specification to be used with IPv4. The RFC allots a special prefix for anycast, which would make an anycast address recognizable as such based on the prefix. Anycast was meant to be used for services such as DNS and HTTP. The RFC discusses possible modifications to TCP to deal with these addresses that are not globally unique.
In practice, anycast has not been implemented as it was designed to be. Often a method called shared unicast address is chosen. This method is implemented by assigning a regular unicast address to multiple interfaces and creating multiple entries in the routing table. In this case the network and transport layer assume that it is a globally unique IP address.
From the beginning, the IPv6 developers considered anycast to be incorporated in the network layer according to RFC 1546. No special prefix was assigned. IPv6 anycast addresses are in the same address range as global unicast addresses, and each participating interface must be configured to have an anycast address. Within the region where the interfaces containing the same anycast addresses are, each host must be advertised as a separate entry in the routing tables.
Anycast Use Cases
Within one network where a group of routers can provide access to a common routing domain, they can be assigned a single address. When a client sends a packet to this address, it will be forwarded to the next available router. One example is the 6to4 relay anycast address that is specified in RFC 3068. The Mobile IPv6 specification also uses anycast addresses.
Multicast Address
This section covers the multicast address format. For a description of multicast and Multicast Listener Discovery (MLD), also known as Multicast Group Management, refer to the relevant RFCs.
A multicast address is an identifier for a group of nodes identified by the high-order byte ff, or 1111 1111 in binary notation. The multicast prefix is ff00::/8. A node can belong to more than one multicast group. When a packet is sent to a multicast address, all members of the multicast group process the packet. Multicast exists in IPv4, but it has been redefined and improved for IPv6.
Multicast Address Format
The first byte identifies the address as a multicast address. The next four bits are used for Flags, defined as follows:
- The first bit of the Flag field must be zero; it is reserved for future use.
- The second bit indicates whether this multicast address embeds the Rendezvous Point. A Rendezvous Point is a point of distribution for a specific multicast stream in a multicast network (RFC 3956).
- The third bit indicates whether this multicast address embeds prefix information (see also RFC 3306).
- The last bit of the Flag field indicates whether this address is permanently assigned, one of the well-known multicast addresses assigned by the IANA—or a temporary multicast address. A value of zero for the last bit defines a well-known address; a value of one indicates a temporary address.
The Scope field is used to limit the scope of a multicast address.
Well-Known Multicast Addresses
According to RFC 4291, the last 12 bits of the address carry the multicast group ID. RFC 3307, "Allocation Guidelines for IPv6 Multicast Addresses," refers to a 32-bit group ID. RFC 2375 defines the initial assignment of IPv6 multicast addresses that are permanently assigned. Some assignments are made for fixed scopes, and some assignments are valid over all scopes.
| Multicast Address | Description |
|---|---|
FF02::1 |
All nodes on the local network segment |
FF02::2 |
All routers on the local network segment |
FF02::5 |
All OSPF routers |
FF02::6 |
All OSPF designated routers |
FF02::9 |
All RIPng routers |
Conclusion
This overview has covered the fundamental concepts of IPv6 and the compelling reasons for migrating from IPv4. We've explored the extended address space, simplified header format, autoconfiguration capabilities, and the various address types including unicast, multicast, and anycast.
Key takeaways include:
- IPv6 provides virtually unlimited address space with 128-bit addresses
- Stateless Address Autoconfiguration (SLAAC) simplifies network management
- The simplified header format improves routing efficiency
- IPv6 eliminates the need for NAT, restoring end-to-end connectivity
- Multiple address types support various networking scenarios
- Transition mechanisms allow gradual migration from IPv4
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